Traditional metabolic engineering has often focused on the rational design of metabolic pathways, relying on extensive a priori knowledge of cellular mechanisms in order to redirect metabolite flow, revise metabolic regulation, or introduce new pathways to achieve a particular phenotype. In recent years, however, considerable advances in molecular biology and the growing availability of annotated genome sequences have made combinatorial methods of metabolic engineering an increasingly attractive approach for strain improvement.
L-tyrosine remains a valuable target compound for microbial production. L-tyrosine serves as a dietary supplement and a valuable precursor for a myriad of polymers, adhesives and coatings, pharmaceuticals, biocosmetics, and flavonoid products, and as such, there has been significant industrial interest in developing fermentation based processes for its synthesis (Leonard, Lim et al. 2007; Qi, Vannelli et al. 2007; Sariaslani 2007; Vannelli, Wei Qi et al. 2007; Leonard, Van et al. 2008).